As prints produced by laser printers approach the image quality of traditional photographic printing, they have taken over an increasing share of the photographic print market. Traditional photographic prints come in different degrees of glossiness, typically glossy, semi-gloss and matte, each using a different grade of paper.
Using different grades of paper to achieve different degrees of glossiness in a laser printer is not so simple, since toners with desirable properties, for example durability, may themselves produce a glossy surface, even on matte paper (or vice-versa). PCT publication WO 01/56806 the disclosure of which is incorporated herein by reference, describes a way to overcome that problem by using a layer of toner that is thin compared to the roughness of the paper or other printing media, so that it acquires the same glossiness as the underlying paper. In any case, inexpensive printers do not generally have several input trays which the printer can automatically choose between. So making prints with different degrees of glossiness by using different grades of paper would require keeping two or three different grades of paper on hand, and hand or machinefeeding the desired paper for each print.
Van Goethem et al, in U.S. Pat. No. 6,101,345, describe varying the glossiness of images printed by a laser printer by varying the fusing temperature, or varying the speed at which the paper passes through the fuser.
Bengston, in U.S. Pat. No. 6,438,336, describes achieving multiple gloss levels on a single image, for example by passing the paper through the printer one time for each gloss level, and varying the fusing temperature on each pass. The disclosures of both these patents are incorporated herein by reference,
Several patents describe ways to achieve uniform levels of gloss on an image, when the toner is glossy, but some parts of the image are devoid of toner. Lamination is one option, but is not practical on inexpensive printers. Another option, described by WO 01/56806, is to apply a transparent toner, with the same glossiness as the actual toner, to those parts of the image that are lacking toner. Alternatively, such a glossy coating can be applied to the whole page as an undercoat, before printing the image, or as an overcoat. Such glossy overcoats and undercoats are useful for making the entire image uniformly glossy, whether or not the toner is glossy. But they are not useful if a uniform matte image is desired, and the toner is glossy and/or the paper is glossy.